Ultrasonic Sensor Detecting Air Bubbles in Liquid Flow

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Solution Overview

Problem

Current methods for detecting and quantifying air bubbles and particles in liquid streams are either invasive, costly, or lack efficiency in medical and industrial applications, particularly in real-time monitoring and fluid opacity.

Innovation Solution

A non-invasive ultrasonic system using piezoelectric transmitter and receiver elements outside a flowing liquid tube, which separates signal components to detect and quantify air bubbles and particles through ultrasonic energy transmission and reception, employing a microprocessor for digital data analysis and self-check functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If invasive detection methods are used to detect air bubbles and particles, then detection reliability is improved, but device complexity and risk of contamination increase

Engineering Contradiction:
Improvedetection reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses the tube wall as an intermediary medium to transmit ultrasonic energy from external transducers to the liquid flow. This allows detection without direct contact between sensors and liquid, eliminating contamination risks while maintaining detection reliability through the mediating ultrasonic waves that pass through the tube wall.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces invasive mechanical sensors with non-contact ultrasonic transducers that operate externally. This substitution eliminates the need for sensors to physically contact the liquid flow, reducing device complexity inside the tube while maintaining detection reliability through acoustic wave transmission.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If non-invasive ultrasonic detection is used, then ease of operation and lack of contamination are improved, but signal detection precision deteriorates due to tube wall interference

Engineering Contradiction:
Improveease of operationVSAvoidsignal detection precision
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent employs signal processing techniques that analyze multiple ultrasonic signal parameters (amplitude, frequency, phase) to distinguish bubble/particle signals from tube wall interference. By changing how signal parameters are measured and interpreted, the system maintains precision despite the added complexity of external detection.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system uses feedback mechanisms to continuously monitor and adjust detection thresholds based on baseline tube wall characteristics. This allows the system to adapt to specific tube wall properties and maintain high measurement precision for bubble and particle detection despite external operation.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If signal separation into DC and AC components is implemented, then measurement precision for bubble detection is improved, but device complexity increases

Engineering Contradiction:
Improvebubble detection precisionVSAvoidsignal processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the ultrasonic signal into distinct DC and AC components for separate analysis. The DC component provides baseline information about tube wall characteristics while the AC component captures dynamic bubble/particle events. This segmentation improves detection precision by isolating relevant signal features.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system extracts and analyzes only the AC component of the signal for bubble detection, separating it from the DC baseline. This extraction approach focuses computational resources on the most relevant signal portion containing bubble information, improving precision without requiring full-signal processing.

Inventive Principle:
Principle #2Taking out (Extraction)

4Productivity

If continuous ultrasonic transmission is used for real-time monitoring, then productivity is improved, but energy consumption increases

Engineering Contradiction:
Improvereal-time monitoring capabilityVSAvoidenergy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic ultrasonic transmission with appropriate pulse intervals rather than continuous transmission. This allows real-time monitoring capability through repeated measurements while reducing overall energy consumption by allowing the system to operate in low-power states between transmission cycles.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system maintains continuous monitoring capability through rapid sequential measurements that provide real-time data on bubble and particle presence. The useful detection action continues without interruption even though actual ultrasonic transmission occurs in periodic bursts, balancing productivity with energy efficiency.

Inventive Principle:
Principle #20Continuity of useful action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables continuous, contamination-free monitoring of air bubbles and particles in various fluids, including opaque liquids, with high sensitivity and accuracy, and provides reliable size and volume quantification, suitable for medical and industrial applications.

Implementation Method 1

The sensor has piezoelectric transmitter and receiver elements. Energy in the ultrasonic frequency range is supplied to the transmitter element which transmits the ultrasonic energy through the tube wall and the liquid flowing in the tube to the receiver element.

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

Energy in the ultrasonic frequency range is supplied to the transmitter element which transmits the ultrasonic energy through the tube wall and the liquid flowing in the tube to the receiver element.

Methodology Applied
Scientific EffectPiezoelectric effect: Converse Piezoelectric Effect

Implementation Method 3

Energy in the ultrasonic frequency range is supplied to the transmitter element which transmits the ultrasonic energy through the tube wall and the liquid flowing in the tube to the receiver element.

Methodology Applied
Scientific EffectUltrasonic wave propagation: Ultrasound

Data Source

PatentEP2126557B1Ultrasonic system for detecting and quantifying of air bubbles/particles in a flowing liquid
Publication Date: 2021.07.14 FRESENIUS MEDICAL CARE HOLDINGS INC
  • EP2126557B1 patent drawingFigure 1
  • EP2126557B1 patent drawingFigure 2~3
  • EP2126557B1 patent drawingFigure 4~5

AI summary

A system using ultrasonic energy for detecting and quantifying air bubbles and/or particles in a liquid flowing in a tube by a non-invasive and non- destructive technique has an ultrasonic sensor having piezoelectric transmitter and receiver elements placed opposing on the outside of the tube wall and energy in the ultrasonic frequency range is transmitted from the transmitter element to the receiver element. The received ultrasonic energy is amplified and detected and preferably split into a steady state (DC) component and a varying or transient (AC) component respectively indicative of the absence and the presence of an air bubble or a particle in the liquid. The two components of the signal are applied to an A/D converter whose output is supplied to a microprocessor which uses the digital data that corresponds to the presence of the varying transient component to indicate the presence of an air bubble and/or a particle and to measure its characteristics. The presence of the steady-state component indicates that the system is operating properly to providing a continuous self check against any system malfunction.